Problem: The diagonal of a square is $\sqrt{2}$ inches long. How many inches long is the side of the square?
Explanation: Since a diagonal of a square breaks up the square into two 45-45-90 triangles, a diagonal is $\sqrt{2}$ times longer than a side. Thus, the length of a side of the square is $\sqrt{2}/\sqrt{2}=\boxed{1}$ inch.